Cellulose, which is a biomass present in large amounts in nature, is without exception in the form of nanofibers referred to as microfibrils at the time fiber is formed by biosynthesis, and these nanofibers are characterized by growing into larger units of fibers by clustering in the direction of the fiber. Bundles of fibers formed in this manner are in a dry state, and primarily function as sturdy structural materials of plants. In these cellulose macro-structural materials, since nanofibers are strongly clustered by bonding forces mainly mediated by hydrogen bonds between the surfaces thereof, they are unable to easily disperse into individual nanofibers.
Patent Document 1 discloses a technology for obtaining nanofibers by treating universally acquirable plant-based purified cellulose (such as wood pulp or linter pulp) with a high-pressure homogenizer. On the other hand, Patent Document 2 and Non-Patent Document 1 disclose a method for pulverizing cellulose using chemical treatment conditions (acid hydrolysis method).    [Patent Document 1] Japanese Unexamined Patent Application, First Publication No. S56-100801    [Patent Document 2] Published Japanese Translation No. H9-508658 of PCT International Publication    [Patent Document 3] Japanese Patent Application No. 2006-169649    [Non-Patent Document 1] O. A. Battista, Ind. Eng. Chem., 42, 502 (1950)    [Non-Patent Document 2] Saito, T., Nishiyama, Y., Putaux, J. L., Vignon, M., Isogai, A.: “Homogeneous Suspensions of Individualized Microfibrils from TEMPO-Catalyzed Oxidation of Native Cellulose”, Biomacromolecules, 7(6), 1687-1691 (2006)    [Non-Patent Document 3] Saito, T., Kimura, S., Nishiyama, Y., Isogai, A., “Cellulose Nanofibers Prepared by TEMPO-Mediated Oxidation of Native Cellulose”, Biomacromolecules, 8(8), 2485-2491 (2007)